1. Field of the Invention
The invention relates to methods and devices for handling an extended proxy information item where the devices are based on nodes and or proxy mesh gates of a wireless mesh network.
2. Description of the Related Art
In recent years, an Institute of Electrical and Electronics Engineers Standard 802.11s was developed that defines a usage of a mesh network topology with nodes/mesh stations in the mesh network serving as a relay for the propagation of messages. In order to connect such a mesh network to an external station located outside the mesh network proxy, mesh gates are implemented at the border of the mesh network that forward messages from outside to inside the mesh network and vice versa. The mesh proxy gate may change the message content, such as address translation or protocol translation.
A draft D11.0 of the IEEE 802.11s standard defines for WLAN mesh networks (WLAN—Wireless Local Area Network) a proxy information and proxy update PXU and proxy update confirmation PXUC elements. Proxy information consists of a proxy Media Access Control (MAC) address of the proxy mesh gate and an external MAC address of the external station, together with an optional lifetime of this proxy information. By using the proxy update PXU and proxy update confirmation PXUC elements the proxy information is made available to other nodes in the mesh network, whereby the other nodes are informed about which external addresses can be reached through which (proxy) mesh gate.
The proxy mesh gate G1 that proxies an external MAC address E1 can send a corresponding proxy update element. However, some other mesh station M1 in the wireless mesh network might also send this proxy information about the external MAC address of the external station and the proxy MAC address of the proxy mesh gate G1 (see FIG. 1). Dashed lines show a communication connection, such as WLAN mesh links.
However, a mesh station M1 might not have received a proxy update element from the mesh proxy gate G1 that changed the proxy information about the mesh proxy gate G1 and external MAC address E1 (for instance, the deletion of the proxy information). As a result, the mesh station might send a proxy update element with outdated proxy information on the mesh proxy gate G1 and external MAC address E1. A recipient of both proxy update elements cannot recognize the wrong chronological order and will reestablish the proxy information, which is not correct.
In the current draft, a specification of the proxy update element defines a field called PXU Sequence Number (8 bit long). However, this field is used only as a proxy update identifier, which identifies the received proxy update element in a proxy information confirmation (PXUC) element that is sent to acknowledge receipt of the proxy update element.
The messages of the path selection protocol Hybrid Wireless Mesh protocol (HWMP) of IEEE 802.11s can also contain proxy information. It always contains a HWMP sequence number, but this sequence number is only used as sequence number for the forwarding information, not for the proxy information.
US 2010/013 discloses a method for transmitting a beacon containing routing information in a mesh sensor network, where the routing information includes a sequence number that is ignored by a receiving sensor node in cases in which the sequence number corresponds to a previous sequence number.